Journal
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume 143, Issue 16, Pages 6123-6139Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jacs.1c00211
Keywords
-
Categories
Funding
- Center for Light Energy Activated Redox Processes (LEAP), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences [DE-SC0001059]
- U.S. Office of Naval Research [N00014-20-1-2116]
- U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design Award [70NANB10H005]
- Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource [NSFECCS-1542205]
- Northwestern University Materials Research Scienceand Engineering Center [NSF DMR-1720139]
- Northwestern U. National Science Foundation (NSF) [NSF CHE-1048773]
- Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF) [NNCI-1542205]
- State of Illinois
- International Institute for Nanotechnology (IIN)
- Department of Energy [DE-AC02-05CH11231]
- DOE Office of Science [DE-AC02-06CH11357]
- MRSEC Program of the Materials Research Center at Northwestern University [NSF DMR-1720139]
- China Scholarship Council [201906070056]
- Open Foundation of Key Laboratory of Multispectral Absorbing Materials and Structures, Ministry of Education [ZYGX2019K009-1]
- Office of the Provost
- Office for Research
- Northwestern University Information Technology
Ask authors/readers for more resources
The study found that combining the π-extension and halogenation strategies of end-capping groups (EG) in organic solar cells significantly impacts optical absorption, leading to an increase in power conversion efficiency (PCE).
The end-capping group (EG) is the essential electron-withdrawing component of nonfullerene acceptors (NFAs) in bulk heterojunction (BHJ) organic solar cells (OSCs). To systematically probe the impact of two frequent EG functionalization strategies, pi-extension and halogenation, in ADAD-A type NFAs, we synthesized and characterized four such NFAs: BT-BIC, LIC, L4F, and BO-L4F. To assess the relative importance of these strategies, we contrast these NFAs with the baseline acceptors, Y5 and Y6. Up to 16.6% power conversion efficiency (PCE) in binary inverted OSCs with BT-BO-L4F combining pi-extension and halogenation was achieved. When these two factors are combined, the effect on optical absorption is cumulative. Single-crystal pi-pi stacking distances are similar for the EG strategies of pi-extension. Increasing the alkyl substituent length from BT-L4F to BT-BO-L4F significantly alters the packing motif and eliminates the EG core interactions of BT-L4F. Electronic structure computations reveal some of the largest NFA pi-pi electronic couplings observed to date, 103.8 meV in BT-L4F and 47.5 meV in BT-BO-L4F. Computed electronic reorganization energies, 132 and 133 meV for BT-L4F and BT-BO-L4F, respectively, are also lower than Y6 (150 meV). BHJ blends show preferential pi-face-on orientation, and both fluorination and pi-extension increase NFA crystallinity. Femto/nanosecond transient absorption spectroscopy (fs/nsTA) and integrated photocurrent device analysis (IPDA) indicate that pi-extension modifies the phase separation to enhance film ordering and carrier mobility, while fluorination suppresses unimolecular recombination. This systematic study highlights the synergistic effects of NFA pi-extension and fluorination in affording efficient OSCs and provides insights into designing next-generation materials.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available